Improved apparatus for bleaching paper-pulp and drying paper



L. DODGE.

Bleaching Apparatus. I

No. 56,732. r H Patented July 31, I866;

Witnesses= oimlnvencon I l v h AM- PHOTO-LITH 0. COJLY- (0550 RNE'S' PRUCESSY) UNITED STATES PATENT OFFIGEQ LEVI DoDeE, 0F WATERFORD, NEW YORK.

Specification forming part of Letters Patent No. 56,732., dated July 31, 1866.

Fig. 2 a transverse vertical section, of an ap paratus constructed in accordance with my invention.

The nature of my invention consists in the peculiar method of drying paper in sheets, and especially that kind of paper known to the trade as straw-board, in the manner and by the means as hereinafter' explained, so that the apparatus may be used at the same time as a means of bleaching the straw or other material which is to be used in the manufacture of such paper or board.

The bestprocess for drying at present consistsv of a series of heated cylinders, each intended for drying one sheet of paper, geared together, with cloth running against them by means of friction-rollers, so that the sheet of paper is kept in close contact with the cylinder on which it is placed until dry. The fact of the paper sticking to the cylinder when wet prevents its being carried from one cylinder. to another. These rolls or cylinders require constant attention, as the paper is liable to be torn if not taken off as soon as it is dry, and therefore every few cylinders must be attended by a man whose business it is to take off the dry paper and put on fresh.

The objections to this process are that the apparatus itself is expensive, and that by the handling of the paper in its wet state, as above mentioned, the stock is often torn orotherwise damaged.

One of the objects of my invention is to remedy these defects, and the other is to effect such a combination in the apparatus that the same cylinder which is used for drying the pulp which has been molded into sheets may at the same time be used for the bleaching of the straw or other material which is intended to be manufactured into paper, thus economizing fuel, labor, and space.

To effect these objects I proceed as follows: Instead of a series of small cylinders, I construct one large cylinder,which must be smoothfaced, rotating on which the paper is dried in one revolution, and is then taken off' by a simple arrangement of doffers and other mechanical devices without ,the interposition of handlabor. The stock is also fed to the cylinder by means of a feed-apron, thus obviating the necessity for handling it. The sheet is held closely to the cylinder until the revolution is completed by means of an endless cloth or band and rollers such as are commonly used in machinery of this kind. The speed with which this cylinder revolves must vary in accordance with and in direct proportional ratio to the size of the cylinderthat is to say, the number of revolutions per hour should be so calculated with respect to the diameter of the cylinder and the thickness of the paper that by each revolutionor, in other words, by being carried once around the cylinderthe sheets taken up by the cylinder shall be dry and ready for removal.

I use thechamber of the cylinder thus formed for bleaching purposes, making a man-hole in one end, of the cylinder, instead of in the side, as is ordinarily the case, through which the material to be bleached is introduced in to the chamber. The steam by which the bleaching process is efi'ected, and which also furnishes the heat for drying the paper,enters the chamber through the hollow journals or trunnions of the cylinder.

I am aware that theprocess of bleaching in a revolving cylinder is not new. The difier- .ence, however, between my method and the As it takes nearly as much coal or wood for drying as for bleaching, it will be seen that in the one item of saving of fuel consequent upon the combination of the two operations the method employed by me possesses an important advantage over the old process.

To enable those skilled in the art to fully understand and to use my invention, 1 will now proceed to describe its construction and operation by reference to the drawings.

Ais the largcrevolvin g cylinder, constructed in accordance with the principles above laid down. B is the endless cloth or band, and G U the rollers, by means of which the sheet is kept in close contact with the cylinder during its entire revolution.

D D are springs or doffers, which lift or take up the sheet from the surface of the cylinder after it .is dry and direct its course upon an apron or other suitable device, by means of which it is carried off. These springs or doffers are fastened to and held in place by a bar attached to the frame of the apparatus.

M is the man-hole in one end of the cylinder, through which the material to be bleached is introduced in the cylinder-chamber. The steam which is used for heatingthe cylinder and bleaching the material enters the cylinder through the journals J J.

When the apparatus is in operation the wet sheet is carried, by means of a feed-apron and rollers, to the portion of the endless cloth or band around the drying-cylinder marked B thence it passes in succession through the opening a between the roller 0 and the rear of the doffers D. There it comes in contact with the revolving cylinder A, and, pressed closely to the cylinder by the cloth B, it passes gradually around until it arrives at a, where, being by this time completely dry, it is taken up from the surface of the cylinder by the doffers D, and is then conducted off on a cloth or apron or other suitable arrangement.

The cylinder thus constructed may be of any size. It may be large enough to receive at one time between twenty and thirty sheets of straw-board, while by the old process, as

above explained, one cylinder is required for each sheet. Thus in my apparatus but one steam-packing is used, where between twenty and thirty are required by the old process.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. The method, substantially as herein described, of bleaching the straw or other paper stuff in a revolving steam-cylinder, and of drying the made paper, whereby these two operations are effected simultaneously in one and the same apparatus. the steam used to dry the paper on the cylinder serving ,at the same time to bleach the material in the cylinder, as set forth.

2. The process herein described of dryingpaper in sheets on a drying-cylinder in one revolution thereof-that is, by so regulatingthe velocity of the revolutions of the drying-cylinder with respect to its diameter and the thickness of the paper operated on that the paper being carried around the cylinder once may be dry and ready to be removed.

3. The revolving bleaching-boiler, when the same is constructed with a smooth cylindrical surface, and one or more man-holes in the sides or caps of the boiler, for the introduction into and removal from the boiler of straw or other paper material, as set forth.

4. In combination with the said cylinder or boiler, the use of an endless apron or band and doft'ers for operation as a drying-cylinder, substantially as set forth.

In testimony whereof I have signed my name to this specification before two subscribing witnesses.

LEVI DODGE.

Witnesses:

A. PoLLoK, EDM. F. BROWN. 

